The dumbbell is a very popular exercise and fitness device. It affords both effective and varied fitness training. Such is normally used for light weight lifting with a single arm although they are also deployed in pairs so that both arms may be exercised simultaneously. As the type of exercises which may be involved with dumbbell workouts are varied, it is helpful to have the ability to quickly switch from one weight to another in order to make the most use of the time available for exercise. One way this can be done would be to have a number of dumbbells of varying weights, but this is expensive and creates a storage problem. A means of permitting switching from one weight to another without substantial storage problems is to use weight adjustable dumbbells.
Generally speaking, weight adjustable dumbbells comprise a dumbbell handle which is adapted at both ends to receive one or more weight plates and such may further comprise means of locking and fastening the weight plates into position for safe use. There are many kinds of weight adjustable dumbbells in the market.
For example, reference is made to US200405969A1. This apparatus teaches a device in which it is necessary to set the adjusting mechanism in both ends of the dumbbell handle separately in order that the bolt fixes relative weight plates. It is not convenient and requires additional time to set a certain weight because two separate actions are required.
Reference is also made to US20070184945A, which avoids the above mentioned defects by adopting theory of sinistral and dextral threading. The bolts in the ends of the dumbbell can be moved by dialing the turntable, so that the bolt fixes certain plates of the desired weights. However, because the threading on the thread rod is a continuous line, the weight location is not precise. Precise location of this kind of dumbbell requires adding positioning mechanisms which are complex and expensive.
There are numerous dumbbell variations in the market but none of them allow simultaneous setting of precise and balanced weights. Such would offer a distinct advantage. What is not provided in the prior art is an adjustable weight dumbbell which permits and facilitates rapid and efficient adjustment of the weight plates and also results in a balanced and safe way to change weights with dumbbell apparatus.